Question about Source Probability in MCNP

[Anisur Rahman]

TL;DR Summary

MCNP Source Specification

Here, SP stands for source probability. But probability needs to be normalized. Here values in SP3, SP4 are larger than 1, It means that SP is not ordinary probability here. But what actually SP represent here?

 

[Alex A]

MCNP will normalise them for you. If you have say three bins that are equally likely you can just write 1 1 1 instead of 0.33333 0.33333 0.33334 and if you add a fourth bin you don't have to redo the whole lot. Some of the material card inputs can be decimal percentages and again MCNP will normalise them. So your thinking is right but automatically normalising contributes a lot to the usability of the program.